The Applicant's international patent application published under the number WO 2008/077909 describes a method of retransmission with incremental redundancy for fragmented packets.
The principle described in this patent application consists in assigning an overall retransmission credit to an IP packet so as to correctly forward the set of fragments associated with this packet with a given transmission time span.
A drawback of this solution is that it is highly sensitive to errors related to the fluctuations of the propagation channel in particular for the return pathway. Indeed the retransmission scheme described is based on the assumption of correct receipt of the acknowledgements sent by the receiver, which is not always the case when the propagation channel is disturbed.
Another drawback of this solution is that it engenders protection to errors that is unequal for all the fragments of an IP packet. By assigning an overall retransmission credit for all the fragments of one and the same IP packet, the first fragment transmitted exhibits a much lower probability of error than the subsequent fragments.
This unequal apportionment of the probabilities of incorrect transmission of a fragment is not always desired.